Field of the Invention
Embodiments of the present invention relate to a semiconductor device, a method for installing a heat dissipation member to the semiconductor device, and a method for producing the semiconductor device.
Discussion of the Background
A semiconductor module (semiconductor device) such as a power conversion element mounted with a power semiconductor chip has a heat dissipation member such as a heat dissipation fin placed on a metal substrate of the semiconductor module, so that heat generated from the semiconductor chip is released by the heat dissipation member (see Japanese Patent Application Publication No. 2004-363521 (“Patent Document 1”), for example). Such a configuration can prevent the increase of the temperature of the semiconductor module.
A heat conductive material such as heat conductive grease is applied to the heat dissipation fin or the metal substrate of the semiconductor module prior to placing the heat dissipation fin on the semiconductor module. The heat conductive material is composed of an organic substance, and heat dissipation of the heat conductive material weakens as the coating thickness of the material becomes excessive. For this reason, the heat conductive material needs to be applied in a layer as thin as possible. By fastening the heat dissipation fin to the metal substrate of the semiconductor module with a screw or the like after the application of the heat conductive material, a force to reduce the thickness of the heat conductive material can be generated at the center of the heat dissipation fin immediately below the semiconductor element. As a result, the distance between the metal substrate and the heat dissipation fin decreases, thereby spreading the heat conductive material into a thin layer, further improving the ability to release heat generated from the semiconductor element (see Japanese Patent Application Publication No. 2000-058727 (“Patent Document 2”), for example).
In addition to using the technology disclosed in Patent Document 2 in which the thickness of the heat conductive material is reduced by changing the shape of the metal substrate (metal base) in the thickness direction, application of a heat conductive material is possible by controlling the shape and thickness of a metal substrate using a metal mask.
Patent Document 2, however, needs to form projections, mounting holes, and the like on the metal base in order to change the shape of the metal base in the thickness direction, and needs to prepare a mask even when using a metal mask. Forming projections, mounting holes and the like and preparing a mask as described above involve a lot of effort, and thus lead to an increase in production cost.